1. Field of the Invention
The present invention relates generally to an output mode switching apparatus adapted for switching between different output modes of an electric tool. In accordance with at least one of the output modes, the electric tool intermittently provides an impact output while continuously outputting a torque output.
2. The Prior Arts
A conventional structure of the electric tools such as electric drills or electric wrenches is typically featured with a structure for transmitting a driving power from a motor to an output shaft for achieving a speed variation (acceleration or deceleration). Further, in order to more tightly lock screws or more conveniently remove the tightly locked screws, some of the electric tools are also provided with an impact function. Such an electric tool is adapted for providing an impact on the screw at the moment of locking the screw, so as to more tightly lock the screw, or providing an impact on the screw at the moment of unscrew the screw to make it loose, so as to more conveniently remove the screw away.
Generally, a typical electric tool having an impact function includes a power unit, a transmission shaft, an intermediate shaft, a hammering seat and an output shaft. The power unit includes a motor, a first planetary gear set, a second planetary gear set, and a clutch mechanism. The clutch mechanism includes a clutch disk. When the clutch disk is axially moved to a first position, the electric tool is switched to a first output mode, in which the transmission shaft is coupled with the second planetary gear set, and the transmission shaft is engaged with the output shaft. In this case, the motor outputs a driving power via the first planetary gear set, the second planetary gear set, the transmission shaft, and the output shaft for continuously driving a tool bit to rotate with a low rotation speed. Correspondingly, the electric tool can be operated serving as an electric drill. Further, when the clutch disk is axially moved to a second position, the electric tool is switched to a second output mode, in which the transmission shaft is detached from second planetary gear set and the output shaft at the same time. In this case, the motor outputs the driving power via the first planetary gear set, the second planetary gear set, the transmission shaft, the intermediate shaft, the hammering seat, and the output shaft, for driving the tool kit to rotate with a high rotation speed and driving the tool kit to intermittently apply an impact. Correspondingly, the electric tool can be operated serving as an impact screw driver.
However, such an electric tool as discussed above further requires a switching apparatus for switching between the two output modes. Unfortunately such a switching apparatus is often complex and expensive.